This invention relates to ultrasonic diagnostic imaging systems and, in particular, to ultrasonic diagnostic imaging systems which automatically define the borders and boundaries of structures within an ultrasonic image.
Many ultrasonic diagnostic procedures in which bodily functions and structures are quantified rely upon clear delineation and definition of the body structures and organs which are being measured. When the quantification or measurement procedure uses static images or a small set of measurements, the delineation of the bodily structure being measured can be done manually. An example of such a procedure is the obstetrical measurements of a developing fetus. Static images of the developing fetus can be acquired during periods when fetal activity is low. Once an image is acquired, only a few circumference or length measurements are usually required to compute development characteristics such as gestational age and anticipated delivery date. These measurements can readily be made manually on the fetal images. Other diagnostic procedures, particularly those involving measurements of the heart and its functioning, present a further set of difficulties. The heart is always beating and hence is always in motion. As it moves, the contours of the heart constantly move and change as the organ contracts and expands. To fully assess many characteristics of cardiac function it is necessary to evaluate many and at times all of the images acquired during the heart cycle (one heartbeat), which can amount to thirty to one hundred and fifty or more images. The structure of interest such as the endocardium, epicardium or valves must then be delineated in each of these images, a painstaking, time-consuming task. Since these structures are constantly in motion, they appear slightly different in each image acquired during the cardiac cycle, and can also vary significantly from one patient to another. While applications such as obstetrical procedures would benefit from a processor which automatically delineates specific anatomy in an ultrasonic image, cardiac diagnosis would benefit even more so.
In order to be able to automatically delineate features in an image, it is necessary for the features to be clearly shown in the image. If the features are unclear the automatic process can fail, requiring user input for the delineation process or, worst of all, requiring the user to resort to a manual technique. It would be desirable for the user to be informed by the ultrasound system when images suitable for feature delineation are being acquired. Furthermore, it is desirable that images best suited for the intended diagnostic procedure be displayed and analyzed.
In accordance with the principles of the present invention, the end diastole and end systole images from an acquired cardiac loop are shown side by side on an image display for automatic border tracing. The cardiac loops may be first acquired then processed for automatic border definition, or the acquired images can be processed in real time to indicate their suitability for automatic border detection as they are acquired. The border tracings can be used to calculate ejection fraction in real time.